Physical servers in a network may be located in a rack unit that houses a plurality of servers. The physical servers may connect to a top of rack (ToR) switch that routes communications between the servers as well as to other external network elements. Additionally, the physical servers may be configured to host one or more virtual machines that may be arranged in one or more virtual networks or subnets. Upon joining the network, the virtual machines are assigned context identifiers, such as an Internet Protocol (IP) address and subnet. The physical servers may also be configured to host corresponding virtual switches and a virtual supervisor module. The virtual switches enable data communications between local virtual machines. In addition, the virtual switches need to obtain the context identifiers of the virtual machines to route communications between the virtual machines to external entities via the directly attached ToR switch.